'Moodus Noises' Strike Again

Small Quake Shakes East Haddam Residents

March 24, 2011|By ERIK HESSELBERG, Special to The Courant, The Hartford Courant

EAST HADDAM — — A loud booming sound that shook the hills Wednesday night, and that many thought was an explosion, was produced by a small earthquake, according to seismologists — a phenomenon known as the Moodus Noises.

According to scientists from Boston College's Weston Observatory in Massachusetts, at 8:42 p.m. the Moodus area registered a 1.3 magnitude earthquake. The epicenter of the quake was 4 miles east of Moodus at a depth of a little more than 3 miles, scientists said.

The tremor — reported as an explosion by dozens of residents — shook houses in the Moodus Reservoir area and sent emergency personnel rushing all over town in search of the source.

Craig Mansfield, the town's emergency management director, said that more than 30 firefighters searched one neighborhood after another for two hours looking for what they thought was a propane tank explosion. "People were describing it like what they heard and felt during the Kleen Energy plant explosion" in nearby Middletown, Mansfield said. "We kept looking and looking without finding anything."

Aware of the town's history of tremors and quakes, Mansfield began to suspect another cause — a geological phenomenon known locally as the "Moodus Noises," in which small earthquakes produce audible sounds.

"You hear old-timers talk about feeling their house shake and hearing loud groans, but in all my 23 years with the town, I've never experienced anything like this," he said. He contacted the U.S. Geological Survey Wednesday night, and Thursdy morning it confirmed that the area had experienced a small earthquake. No damage was reported, Mansfield said.

Moodus gets its name from these audible groans from deep in the earth. The native tribes called the area Machemoodus or Mackimoodus, which means the "place of many noises," and ascribed the eerie rumblings to an angry spirit known as "Hobbamocko."

Connecticut geologist Jelle Zeilinga DeBoer, professor emeritus at Wesleyan University, has studied the Moodus Noises for years and writes about the phenomenon in a new book, "Stories in Stone: How Geology Influenced Connecticut History and Culture." DeBoer writes that Connecticut has had a fair amount of seismic activity, with at least 137 recorded shocks since 1678.

The most famous tremor was the earthquake of May 16, 1791, whose epicenter was in Moodus. The quake toppled chimneys, collapsed stone walls and even caused fissures in the ground. Aftershocks, continuing for several days, were felt 25 miles away on the shoreline in Branford. Scientists estimate that the May 1791 earthquake had magnitude of 4.3 on the Richter scale.

Engineers noted the area's seismic past in designing the Yankee Atomic Nuclear Plant on the banks of the river in Haddam Neck, which went online in 1968. A seismic network was installed around the plant, which, in the early 1980s, recorded "intense swarms of micro-earthquakes," according to DeBoer.

The nuclear plant shut down in 1998 and has since been decommissioned, but highly radioactive spent fuel rods from 30 years of operation are stored onsite in protective steel and concrete casks.